1. Field
Various examples described herein relate generally to features for preventing or reducing damage due to forces and moment loads applied to a motor hub within a motor system, and in particular, support pads for supporting portions of a motor against forces and moment loads.
2. Description of Related Art
Magnetic disc drives are used for magnetically storing information. In a magnetic disc drive, a magnetic disc rotates at high speed and a transducing head “flies” over a surface of the disc. This transducing head records information on the disc surface by impressing a magnetic field on the disc. Information is read back using the head by detecting magnetization of the disc surface. The transducing head is moved radially across the surface of the disc so that different data tracks can be read back.
Over the years, storage density has tended to increase and the size of the storage system has tended to decrease. This trend has led to greater precision and lower tolerance in the manufacturing and operating of magnetic storage discs. For example, to achieve increased storage densities the transducer head is placed increasingly close to the surface of the storage disc to track increasingly densely positioned data tracks. As the density of the data tracks increases it is generally desired that the disc rotate substantially in a single plane with reduced run-out. A slight wobble or non-repeatable run-out in disc rotation can limit track spacing to account for misreads by the transducer head, thereby lowering track density. Accordingly, it is desired to reduce and minimize non-repeatable run-out in the system.
From the foregoing discussion, it can be seen that the stability of the motor and bearing assembly supporting the storage disc is of importance. One typical bearing assembly includes a fluid dynamic bearing. A fluid dynamic bearing provides a lubricating fluid such as gas or a liquid in a bearing gap between a fixed member and a rotating member. In one exemplary bearing assembly, a hub attached to a shaft is rotatably mounted with a sleeve, where bearing regions are included in a radial gap between the shaft and the sleeve as well as in an axial gap between planar surfaces of the sleeve and hub. Moment loads as a result of various conditions or events such as operational shock, disc installation, clamp installation, clamp/screw installation, and the like, may cause stress on the joint between the hub and shaft. Stress on the hub/shaft joint due to such a moment load during relative rotation or otherwise may result in several deleterious effects on the motor including, for example, instability of the bearing assembly support system. In particular, a moment load may pass through the hub/shaft joint and cause temporary or permanent changes in the hub/shaft joint or the bearings leading to run-out accuracy (TIR) changes relative to the axis of rotation, or the like.
Accordingly, devices and methods for supporting a hub (or other motor member) from external forces and reducing the potential for change or damage to the operation of the motor resulting from an external force are desired.